I think you do need to stay grounded and keep a sensible view about what you're doing and accept other people may not agree that you're the best thing ever.

But at the same time I think you have to believe in your own head that you are (or at least can be) brilliant, otherwise all the frustrations and disappointments you inevitably experience would be too much to bear.

other people could potentially do what I do better than me, but no one seems to be trying. So I'll carry on until someone nicks all my ideas and becomes more succesful with them. Then wait for a retrospective critical reappraisal.

I predict I'll break even on my musical investment sometime within the next 30 years.

I'd definitely quit- or change the personnel, depending on how large a part I played in the band.
I never understand it when speaking to people upon hearing they're in a band, and they say 'yeah, we're kind of like funky-rock, it's a bit shit...' why they don't go and create something they're actually proud of being a part of. It must be the worst thing ever going onstage and preying no-one you know shows up.